Technical Field
The present disclosure relates to a dynamic vibration absorbing device, particularly to a dynamic vibration absorbing device that absorbs torsional vibration.
Background Information
A well-known dynamic vibration absorbing device, such as a dynamic damper, includes a rotary part (a damper plate 52), an inertia part (a pair of inertia rings 53 and a pair of lid members 54) and an elastic part (coil springs 55) (see Japan Laid-open Patent Application Publication No. 2015-17671). In this dynamic damper, the inertia part is moved in a circumferential direction through the elastic part when torsional vibration is transmitted to the rotary part. The torsional vibration is absorbed by the movement of the inertial part.
In the well-known dynamic vibration absorbing device, the inertia part is moved in the circumferential direction so as to absorb the torsional vibration transmitted to the rotary part. In the dynamic vibration absorbing device, the inertia part is moved in the circumferential direction, while distance between the inertial part and a rotational center is kept constant.
When the mass of the inertia part and the stiffness of the elastic part are herein assumed to be constant, the inertia part is effectively actuated at a predetermined rotational velocity, that is, a resonant rotational velocity. Put differently, the well-known dynamic vibration absorbing device effectively absorbs torsional vibration at a single resonant rotational velocity corresponding to the (constant) mass of the inertial part and the (constant) stiffness of the elastic part. Therefore, the well-known dynamic vibration absorbing device has a drawback that the effect of absorbing torsional vibration degrades when the rotational velocity of the rotary part deviates from the resonant rotational velocity.